According to a sharp eyed viewer, a half pack is not quite a halft pack, and yes they are right. A half pack is a little bit more than just a half. Its more of an expression, rather than a mesurement. I will publish the heights that I have come up with, in HO. Obviously there is a difference between a TNT (now CEVA?) 51ft auto half pack and a SPD 1993 era half pack.